Jumped in the first cave I found in creative, just to take a look at ore gen. Not sure what the gen is based on but I found Aluminum at around the same consistency as Iron. Red, black and green ores were fairly common, also about the same consistency, I was seeing at least one type of ore in the same dispersion as coal. Very few blue ores until lower depths, and Yellow ores were fairly common above about 50. Only saw maybe 5 crystals in the cave I was looking through.
As a rough estimate I could probably have collected a stack of each gem, a stack of Aluminum and 5-10 crystals.
As for bugs? All raw ores (gathered through Silk Touch for example) smelt into Aluminum apparently, illustrated HERE. Other than that everything seems in order so far.